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      <title>消息异常处理方案 - 交互式测验</title>
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          <div class="quiz-container">
            <div class="quiz-header">
              <h1>消息异常处理方案 - 交互式测验</h1>
              <p>检验你对文档内容的理解程度</p>
            </div>
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      <script>
        const quizData = [
  {
    "question": "在RocketMQ中，关于同步发送（Synchronous Send）的默认重试机制，以下哪个说法是正确的？",
    "options": [
      "默认情况下不进行任何重试。",
      "默认情况下，同步发送失败会重试2次，总共尝试3次。",
      "重试间隔采用指数退避算法，以避免冲击Broker。",
      "默认情况下，同步发送失败会重试3次，总共尝试4次。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中明确指出，RocketMQ的同步发送默认重试2次，这意味着加上首次发送，总共会有3次尝试。这是为了在遇到瞬时网络抖动或Broker短暂不可用时提高发送成功率。需要注意的是，其重试间隔是固定的，而非指数退避。",
    "source": "文档中「内置重试机制」-「同步发送重试」部分",
    "hint": "文档中提到了同步发送的默认重试次数，注意区分“重试次数”和“总尝试次数”。"
  },
  {
    "question": "与同步发送不同，RocketMQ的异步发送（Asynchronous Send）在默认配置下遇到发送失败时会如何处理？",
    "options": [
      "会自动切换为同步发送模式并进行重试。",
      "默认不进行重试，需要开发者手动开启并配置重试次数。",
      "默认重试2次，与同步发送的策略保持一致。",
      "会将失败的消息自动持久化到本地磁盘，等待后续处理。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中明确说明，异步发送默认是不进行重试的。这是因为异步发送的设计初衷是为了非阻塞和高吞吐量，将失败处理的逻辑交由回调函数（Callback）来决定。开发者可以通过 `producer.setRetryTimesWhenSendAsyncFailed()` 方法来主动开启和配置异步发送的重试。",
    "source": "文档中「内置重试机制」-「异步发送重试」部分",
    "hint": "思考一下异步调用的非阻塞特性，它的默认失败处理策略是否会像同步调用那样阻塞等待重试呢？"
  },
  {
    "question": "在RocketMQ的消费端，当一条消息因为业务处理异常而反复重试，最终超过了设定的最大重试次数后，这条消息会经历什么？",
    "options": [
      "消息会被系统永久丢弃，无法找回。",
      "消费者会继续无限次地重试该消息，直到消费成功。",
      "消息会被投递到一个特殊的队列——死信队列（Dead-Letter Queue）。",
      "该消费者实例会被Broker隔离，不再接收任何新消息。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "为了避免有问题的消息无限次重试从而阻塞整个消费流程，RocketMQ设计了死信队列机制。当一条消息达到最大重试次数后，它会被认为是一条“死信”，并被自动发送到对应的死信队列中。这使得开发和运维人员可以专注于处理这些异常消息，而不会影响正常消息的消费。",
    "source": "文档中「消费重试机制」-「重试次数控制」与「死信队列处理」-「死信队列机制」部分",
    "hint": "当正常的重试流程也无法解决问题时，系统需要一种机制来隔离这些“疑难杂症”消息，以便进行人工干预。这个机制是什么？"
  },
  {
    "question": "根据文档，RocketMQ的死信队列（DLQ）和重试队列（Retry Queue）的命名规则分别是什么？",
    "options": [
      "死信队列: `%DEAD%`+消费组名, 重试队列: `%RETRY%`+Topic名",
      "死信队列: `%DLQ%`+消费组名, 重试队列: `%RETRY%`+消费组名",
      "死信队列: `DLQ_`+Topic名, 重试队列: `RETRY_`+Topic名",
      "两者都使用消费组名作为后缀，但前缀不同。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "文档中明确指出了这两种特殊队列的命名规范。重试队列的名称是 `%RETRY%` 加上消费组的名称，例如 `%RETRY%my-consumer-group`。死信队列的名称是 `%DLQ%` 加上消费组的名称，例如 `%DLQ%my-consumer-group`。这两种队列都是与特定的消费组绑定的。",
    "source": "文档中「消费重试机制」-「重试队列」与「死信队列处理」-「死信队列机制」部分",
    "hint": "这两种特殊的队列都是为某个特定的消费行为服务的，因此它们的命名都与哪个核心概念紧密相关？"
  },
  {
    "question": "关于RocketMQ消费者消费失败后的重试间隔策略，以下描述最准确的是？",
    "options": [
      "重试间隔是固定的，默认为1秒。",
      "重试间隔采用指数退避策略，时间会逐渐拉长，例如第一次10秒，第二次30秒。",
      "每次重试都立即进行，没有任何间隔时间。",
      "重试间隔由生产者在发送消息时指定。"
    ],
    "correctAnswerIndex": 1,
    "explanation": "当消费失败时，为了避免因依赖的下游服务短暂不可用而导致密集的无效重试，RocketMQ采用了指数退避的策略。这意味着每次重试的间隔时间会越来越长（例如：10s, 30s, 1m, 2m ...），给下游系统留出恢复的时间。固定的1秒间隔是同步发送失败时的重试策略，而非消费重试。",
    "source": "文档中「消费重试机制」-「重试间隔」部分",
    "hint": "为了防止因瞬时故障导致消费者在短时间内频繁重试，从而对系统造成冲击，系统采用了一种怎样的智能延迟策略？"
  },
  {
    "question": "在RocketMQ应用中，为什么保证消费逻辑的“幂等性”是一个至关重要的实践？",
    "options": [
      "为了提高消息的压缩率，减少网络传输。",
      "因为Broker的故障转移机制可能会导致消息重复发送。",
      "因为消费重试机制的存在，同一条消息可能被多次投递和消费，幂等性可以防止业务数据因重复处理而出错。",
      "这是RocketMQ协议的强制要求，否则客户端无法连接到Broker。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "幂等性是指对同一个操作执行一次和执行多次的结果是完全相同的。在消息队列中，由于网络问题或消费者异常可能触发重试机制，导致同一条消息被不止一次地投递给消费者。如果消费逻辑不具备幂等性（例如，简单的数据库INSERT操作），重复消费就会导致数据重复或业务逻辑错误。因此，设计幂等的消费逻辑是保证数据一致性的关键。",
    "source": "文档中「消费幂等性保证」-「幂等性问题」部分",
    "hint": "当一条消息因为处理失败而被系统自动“重新投递”时，你的业务代码会面临什么挑战？"
  },
  {
    "question": "为了提高消息发送的可用性，当某个Broker出现高延迟或故障时，RocketMQ Producer提供了哪种机制来智能地规避有问题的Broker？",
    "options": [
      "Producer会自动向NameServer报告故障，由NameServer通知所有客户端。",
      "必须手动修改Producer配置，从地址列表中移除故障Broker。",
      "启用延迟容错机制(`setSendLatencyFaultEnable(true)`), Producer会根据历史发送延迟智能地选择Broker。",
      "Producer会持续重试当前Broker，直到它恢复正常。"
    ],
    "correctAnswerIndex": 2,
    "explanation": "RocketMQ提供了延迟容错（Latency Fault Tolerance）机制。当开启 `producer.setSendLatencyFaultEnable(true)` 后，Producer客户端会记录向每个Broker发送消息的延迟情况。在选择发送队列时，它会倾向于避开那些近期延迟较高的Broker，从而在某个Broker性能下降或“假死”时，能够智能地切换到其他健康的Broker，提升发送的成功率和性能。",
    "source": "文档中「故障转移机制」-「Broker故障转移」部分",
    "hint": "Producer如何像一个有经验的司机一样，“学习”并避开那些“拥堵”的路线（Broker）？文档中提到了一个相关的配置开关。"
  }
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                loadQuestion();
            }
        }
        
        function showHint() {
            const currentQuestion = quizData[currentQuestionIndex];
            if (currentQuestion.hint) {
                hintContainerEl.textContent = currentQuestion.hint;
                hintContainerEl.style.display = 'block';
            } else {
                hintContainerEl.style.display = 'none';
            }
        }

        function showFinalScore() {
            document.querySelector('.quiz-body').style.display = 'none';
            document.getElementById('quiz-footer').style.display = 'none';

            const correctCount = score;
            const totalQuestions = quizData.length;
            const answeredCount = userAnswers.filter(a => a !== null).length;
            const wrongCount = answeredCount - correctCount;
            const skippedCount = totalQuestions - answeredCount;
            const accuracy = totalQuestions > 0 ? Math.round((correctCount / totalQuestions) * 100) : 0;
            const errorRate = totalQuestions > 0 ? Math.round((wrongCount / totalQuestions) * 100) : 0;

            const finalScoreHtml =
                '<div class="final-score-container">' +
                '<h2>答题报告</h2>' +
                '<div class="score-summary">' +
                '<div class="score-card">' +
                '<h3>得分</h3>' +
                '<p>' + correctCount + ' / ' + totalQuestions + '</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>正确率</h3>' +
                '<p>' + accuracy + '%</p>' +
                '</div>' +
                '<div class="score-card">' +
                '<h3>错误率</h3>' +
                '<p>' + errorRate + '%</p>' +
                '</div>' +
                '<div class="score-card score-details">' +
                '<table>' +
                '<tr><td>正确</td><td>' + correctCount + '</td></tr>' +
                '<tr><td>错误</td><td>' + wrongCount + '</td></tr>' +
                '<tr><td>未答</td><td>' + skippedCount + '</td></tr>' +
                '</table>' +
                '</div>' +
                '</div>' +
                '<div class="report-actions">' +
                '<button id="review-btn">回顾测验</button>' +
                '<button class="primary" onclick="location.reload()">再试一次</button>' +
                '</div>' +
                '</div>';

            let reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }
            quizContentEl.insertAdjacentHTML('beforeend', finalScoreHtml);
            document.getElementById('review-btn').addEventListener('click', reviewQuiz);
        }

        function reviewQuiz() {
            const reportEl = document.querySelector('.final-score-container');
            if (reportEl) {
                reportEl.remove();
            }

            document.querySelector('.quiz-body').style.display = 'block';
            document.getElementById('quiz-footer').style.display = 'flex';
            
            currentQuestionIndex = 0;
            loadQuestion();
            updateNavigationButtons(); // Ensure nav buttons are correctly displayed
        }

        // Event Delegation for options
        optionsListEl.addEventListener('click', (event) => {
            if (event.target && event.target.matches('li.option-item')) {
                // Check if the question has already been answered
                if (userAnswers[currentQuestionIndex] === null) {
                    const selectedIndex = parseInt(event.target.dataset.index, 10);
                    selectOption(selectedIndex);
                }
            }
        });

        prevBtn.addEventListener('click', goToPreviousQuestion);
        nextBtn.addEventListener('click', goToNextQuestion);
        hintBtn.addEventListener('click', showHint);
        
        // 初始加载
        loadQuestion();
      </script>
    </body>
    </html>
  